Use your existing technology to backup your office data to a hard drive connected to your home network.
If you own a Virtual Private Network (VPN) capable router and an external networkable hard drive (network-attached storage [NAS]), you already have what you need to backup your office data at home. Routers with a USB port also convert any USB hard drive to a network-attached storage or NAS device.
A VPN allows you to securely transmit and receive data across the public Internet. In this way, it virtually connects your office network to your home network.
Once your VPN is in place and configured, you would use a VPN client (can be a web client) to connect to your home network with just your username and password.
Note that VPN capable routers start at around $100.